WITHOUT CLOSE VESSELS. 403 
narrow chimney outside the wall, te the height of 
about six feet, when I prolonged it about six feet 
more, but in an horizontal direction. For the top 
of this kiln I had a sheet iron cover made, a few 
inches wider than the diameter of the brick work, 
of a convexity of two feet, with a round hole or 
chimney in the centre, one foot high, and nine 
inches diameter, provided with a cover and handle 
similar to that of a canister, and at a foot from the 
extremity of the large cover, are cut out four 
auxiliary chimneys, at equal distances one from 
the other, with a four inch diameter. Four strong 
iron rings are fixed to the cover to receive the 
hooks of a chain, which, by means of a double 
purchase, raises or lowers the cover. 
When this furnace, says Dumas, is filled with 
wood, the cover is lowered down, and some fire- 
brands are precipitated through the central chim- 
ney to the bottom of the kiln; the wood being 
placed so as to leave a sort of funnel open. By 
means of the four blowing air-holes the fire is very 
soon spread in all directions, and its progress is 
to be regulated by shutting or opening the smoke 
and airholes, according to the direction of the wind. 
These rules, which no doubt did answer when 
